when I go into the atmosphere it tells me that the internal memory is not free, but if I go into stock it says that there are 30 GB free on the internal memoryYou will need a bigger SD card, or to reboot to Original Firmware to play some of your games off the internal storage.

I have a SD card in the switchДля Atmosphere требуется карта SD, это не связано с внутренним хранилищем. Все, что является microSD на 64 ГБ или больше, должно подойти
I have very little free space on the atmosphere, but a lot of free space on the stock (non-SD) card, now I can't create saves in the atmosphere, what should I do?
No, I don't have anything there at allПохоже, вы установили слишком много на 30 ГБ "внутреннего хранилища" emuMMC (которое на самом деле является эмулированным "внутренним хранилищем" на SD-карте). Обычно вы хотите сохранить это пространство для сохранений, а не заполнять его играми.
No, I don't have anything there at all
sounds like you are using an emummc and you are not using that space, if your sd card partition is filling up you need a larger card.
Why is my quote in Russian? lol
Which ‘there’ do you mean? Your first post said you had little space ‘on the atmosphere’, by which we assumed you mean Atmosphere’s ‘internal memory’ that is actually part of the SD card:No, I don't have anything there at all